CHIP-8 Assembler/Disassembler

CHIP-8 Assembler/Disassembler

Source Code		Machine Code
;===========================; ; Generate a maze in CHIP-8 ; ;===========================; ; Registers: ; ; V0 used for x ; ; V1 used for y ; ; V2 used for random bit ; ;===========================; TOP: LD I,R3 ; Load sprite address RND V2,01 ; Put random bit in V2 SE V2,01 ; Skip if V2=1 (random) LD I,R1 ; Load a different sprite DRW V0,V1,4 ; Draw at (V0,V1) 4 rows ADD V0,04 ; Add 4 to x coord SE V0,40 ; Skip if at end of V0 JP TOP ; Go back to top LD V0,00 ; At end so go back x=0 ADD V1,04 ; Add 4 to y SE V1,20 ; Skip if end of y (done) JP TOP ; Go back to top END: JP END ; Stay here ... forever R1: DATA 8040 ; Image data R2: DATA 2010 ; Image data R3: DATA 2040 ; Image data R4: DATA 8010 ; Image data		A21E C201 3201 A21A D014 7004 3040 1200 6000 7104 3120 1200 1218 8040 2010 2040 8010

=== Assembler Syntax ===

Code Assembly Description - All numbers are hexadecimal ---- -------- ----------------------------------------- lbl: A label - must not match any other string in the program! nnnn - DATA nnnn Initialize a data word (all values in hex) 0nnn - SYS addr Jump to a machine code routine at nnn. 00E0 - CLS Clear the display. 00EE - RET Return from a subroutine. 1nnn - JP addr Jump to location nnn. 2nnn - CALL addr Call subroutine at nnn. 3xkk - SE Vx, byte Skip If Equal Immediate: Skip next instruction if Vx = kk. 4xkk - SNE Vx, byte Skip If Not Equal Immediate: Skip next instruction if Vx != kk. 5xy0 - SE Vx, Vy Skip If Equal Register: Skip next instruction if Vx = Vy. 6xkk - LD Vx, byte Load Immediate: Set Vx = kk. 7xkk - ADD Vx, byte Add Immediate: Set Vx = Vx + kk. 8xy0 - LD Vx, Vy Load Register: Set Vx = Vy. 8xy1 - OR Vx, Vy Or Register: Set Vx = Vx OR Vy. 8xy2 - AND Vx, Vy And Register: Set Vx = Vx AND Vy. 8xy3 - XOR Vx, Vy XOR Register: Set Vx = Vx XOR Vy. 8xy4 - ADD Vx, Vy Add Register: Set Vx = Vx + Vy, set VF = carry. 8xy5 - SUB Vx, Vy Sub Register: Set Vx = Vx - Vy, set VF = NOT borrow. 8xy6 - SHR Vx {, Vy} Shift Right: Set Vx = Vx SHR 1. 8xy7 - SUBN Vx, Vy Sub Negative Register: Set Vx = Vy - Vx, set VF = NOT borrow. 8xyE - SHL Vx {, Vy} Shift Left: Set Vx = Vx SHL 1. 9xy0 - SNE Vx, Vy Skip If Not Equal: Skip next instruction if Vx != Vy. Annn - LD I, addr Load I Immediate: Set I = nnn. Bnnn - JP V0, addr Jump to V0 with offset nnn. Cxkk - RND Vx, byte Rand: Set Vx to a random number (0 to 255) AND byte value Dxyn - DRW Vx, Vy, n Draw: Display n-byte sprite starting at memory location I at (Vx, Vy), set VF = collision. Ex9E - SKP Vx Skip if Key[Vx]: Skip next instruction if key with the value of Vx is pressed. ExA1 - SKNP Vx Skip if !Key[Vx]: Skip next instruction if key with the value of Vx is not pressed. Fx07 - LD Vx, DT Load Vx from Delay Timer: Set Vx = delay timer value. Fx0A - LD Vx, K Load Vx from next Key: Wait for a key press, store the value of the key in Vx. Fx15 - LD DT, Vx Load Delay Timer from Vx: Set delay timer = Vx. Fx18 - LD ST, Vx Load Sound Timer from Vx: Set sound timer = Vx. Fx1E - ADD I, Vx Add Vx to I: Set I = I + Vx. Fx29 - LD F, Vx Load I from Sprite location: Set I = location of sprite for digit Vx. Fx33 - LD B, Vx Load BCD from X into Memory[I]: Store BCD representation of Vx in memory locations I, I+1, and I+2. Fx55 - LD [I], Vx Save Registers: Store registers V0 through Vx in memory starting at location I. Fx65 - LD Vx, [I] Restore Register: Read registers V0 through Vx from memory starting at location I.

Note: You can convert a binary .ch8 file to hex for the Machine Code window with:

$ od -v -tx1 -An filename

For example:

$ od -v -tx1 -An bin/chip8/games/Maze.ch8 a2 1e c2 01 32 01 a2 1a d0 14 70 04 30 40 12 00 60 00 71 04 31 20 12 00 12 18 80 40 20 10 20 40 80 10